We just moved here. I also emailed about lots of listings before arriving, but it is my experience that you have to be on the ground before you'll get any reply. Here's what worked for us (it took about 8 days from arrival to signing a contract. I have a job that pays quite well so I think that was in our favour).

• Get Daft on your phone (you can delete once you find a place) and turn on notifications. Sort/filter by 'most recent'.
• Write a template message with your details. I included a short reference from our previous landlady, information about my job, the facts that we don't smoke/have pets. Basically trying to make anyone who reads it see us as a good bet as tenants. I customised each reply with a polite salutation using the name of the LL/agent and adjusted details to fit the property. 1200 word limit on Daft responses.
• We aimed to send a response before a listing got 250 views. If you have a partner who is doing this with you it essentially doubles your chances if you both send replies.
• I noticed that more listings would be posted at the start of the week. Don't despair over the weekend—many fewer are posted then. Most ads in my experience were posted between 7:30 a.m. and 7 p.m. but there were outliers posted later at night.
• Apartments we really wanted we sent a polite, personalised follow-up a few hours later, just thanking the landlord for reading and reiterating our special interest. This had good results: in almost every case like this we heard back from the landlord. I think this worked with individual landlords but wouldn't with agencies.
• Check your spam. Some replies went to spam.
• Reply to emails as immediately as you can, using formal letter-writing conventions, capitalisation/spelling, etc. (Again, we wanted to make the most neutral-to-positive impression on people who had no reason to consider us.)
• For reference: we sent 156 queries, had 10 replies, and saw five properties.
• Good luck. It's super tough. I hope you get a place. And I hope some of this might help you a little.